J-aggregates Of Dyes Research Articles

Effects of Plasmon–Exciton Interaction in the Spectra of Light Absorption by Hybrid Systems Consisting of Two- and Three-Layer Organometallic Nanoparticles

The effects of plasmon-exciton interaction on the spectra of light absorption by hybrid systems of two- and three-layer nanoparticles that consist of a metallic nucleus, the outer shells of ordered molecular dye J-aggregates, and an intermediate passive organic spacer between them is analyzed theoretically. It is established that the type of the absorption spectra and the efficiency of a near-field electromagnetic coupling between the particles in the system depends largely on the distance between the centers of concentric spheres and the direction of light polarization.

Nanoscale Photoconverters for the IR Region of the Spectrum Based on Mixed J-Aggregates of Indolenine Dyes

It is shown that anionic indoheptamethine cyanine dyes of different structures form mixed metalcomplex J-aggregates in aqueous solutions under the action of multiply charged inorganic cations. By measuring the photoconductivity of layers from mixed metal-complex J-aggregates, it has been found that the photoresponse of nanoscale photoconverters for the IR region of the spectrum increases significantly in comparison with the indices for the J-aggregate of the individual dye. It is concluded that the formation of new highly organized structures by the self-assemblage of J-aggregates of several dyes can be considered a promising nanotechnology method for the production of organic semiconductors with improved photo properties.

J-Aggregates of Indoheptamethine Cyanine Dye

The effect of doubly charged inorganic and organic cations on the aggregation of anionic indoheptamethine cyanine dyes has been studied in aqueous solutions. It is shown that the effective formation of J-aggregates with narrow exciton absorption bands in the IR region of the spectrum with λmax = 920 nm is characteristic only of a dye with SO 3 - groups in the 6,6′-positions of the benzoindolenine ring. It is found that bis-quaternary salt based on α-picolinium is particularly effective as a J-aggregating agent and causes J-aggregation at a concentration close to the dye concentration. It follows that the introduction of sulfogroups at the 6,6′-positions of the benzoindolenine ring creates optimal conditions for packing the molecules of the indolenine dye into a highly organized structure of a “brickwork” type under the action of multiply charged cations. It is shown that the J-aggregates of the indoheptamethine cyanine dye are photoelectric converters for the IR region of the spectrum.

Fluorescent Cyanine Dye J-Aggregates in the Fluorous Phase.

We present a perfluorocarbon-hydrocarbon amphiphilic cyanine dye that J-aggregates in fluorous solvent. J-Aggregation is a special type of fluorophore aggregation, affording enhanced photophysical properties. Cyanine dyes are excellent J-aggregators in water but, until now, cyanine J-aggregates have not been translated to nonaqueous media. The fluorous phase J-aggregate displays enhanced photostability and processability compared to analogous aqueous aggregates.

Strong difference between optical properties and morphologies for J-Aggregates of similar cyanine dyes

Optical properties and morphologies of molecular aggregates of two similar cyanine dyes (BIC and TDBC) have been studied. The dyes have the same 5,5′,6,6′-tetrachlorobenzimidacarbocyanine chromophore part and differ just in one methyl group in alkyl chains. Due to such a similarity of the dye molecular structures, their aggregates are often supposed to have similar structure. However the difference in optical properties was reported in some publications assuming different structures of the J-aggregates. Indeed, we have found distinct morphologies for BIC and TDBC J-aggregates: spherical species for BIC J-aggregates and rod-like ones for TDBC J-aggregates. The difference in morphologies and, hence, structures is the reason of unlike optical properties of these J-aggregates.

Effect of Electric Field on J-aggregate in Ultrathin Films

In the present paper we have demonstrated the application of electric field towards the reconstruction of J-aggregate of an indocarbocyanine dye onto LB film. Similar approach can also be applied for the improvement of J-aggregate using other molecules.

Полиморфные монослойные и фибриллярные наноструктуры J-агрегатов карбоцианинового красителя

Полиморфные монослойные и фибриллярные наноструктуры J-агрегатов карбоцианинового красителя

Tubular J-aggregates of a new thiacarbocyanine Cy5 dye for the far-red spectral region - a spectroscopic and cryo-transmission electron microscopy study.

The aggregation behavior of a phenol-substituted thiacarbocyanine Cy5 dye (5-chloro-2-[5-[5-chloro-3-(4-sulfobutyl)-3H-benzothiazol-2-ylidene]-3-phenyl-penta-1,3-dienyl]-3-(4-sulfobutyl)-benzothiazol-3-ium hydroxide, inner salt, triethylammonium salt) in aqueous solution is investigated using steady-state absorption, linear dichroism, and fluorescence spectroscopies, as well as cryogenic transmission electron microscopy (cryo-TEM). By increasing the concentration, the dye self-assembles in pure water into dimers and H-aggregates, the latter being uniform particles of ∼2.6 nm size. In the presence of NaCl, two different types of J-aggregates are observed depending on salt concentration (varied from 10 to 100 mM). At low salt concentration (10 mM) a J-aggregate of extended mono-layered sheets prevails, which disappears after a few days, whereas a second type of J-aggregate emerges. Generally, the latter dominates in matured solutions in particular at high salt concentration and seems to be the thermodynamically stable species. This J-aggregate shows three perpendicularly polarized absorption bands and fluoresces in the far-red at around 800 nm. The most intensive and very narrow (fwhm of 238 cm-1) absorption band is centered at 796 nm. Cryo-TEM reveals uniform nanotubes of ∼7 nm diameter and micrometer length. They represent the first tubular cyanine dye J-aggregates that are active in the far-red. Moreover, the studied dye is a prime example of cyanine dyes showing two self-assembly pathways that lead to different species of J-aggregates with distinct optical and morphological properties.

Bright Surface‐Enhanced Raman Scattering with Fluorescence Quenching from Silica Encapsulated J‐Aggregate Coated Gold Nanoparticles

Plexitonic nanoparticles offer variable optical properties through tunable excitations, in addition to electric field enhancements that far exceed molecular resonators. This study demonstrates a way to design an ultrabright surface-enhanced Raman spectroscopy (SERS) signal while simultaneously quenching the fluorescence background through silica encapsulation of the semiconductor-metal composite nanoparticles. Using a multistep approach, a J-aggregate-forming organic dye is assembled on the surface of gold nanoparticles using a cationic linker. Excitonic resonance of the J-aggregate-metal system shows an enhanced SERS signal at an appropriate excitation wavelength. Further encapsulation of the decorated particles in silica shows a significant reduction in the fluorescence signal of the Raman spectra (5× reduction) and an increase in Raman scattering (7× enhancement) when compared to phospholipid encapsulation. This reduction in fluorescence is important for maximizing the useful SERS enhancement from the particle, which shows a signal increase on the order of 104 times greater than J-aggregated dye in solution and 24 times greater than Oxonica S421 SERS tag. The silica layer also serves to promote colloidal stability. The combination of reduced fluorescence background, enhanced SERS intensity, and temporal stability makes these particles highly distinguishable with potential to enable high-throughput applications such as SERS flow cytometry.

Narrow-Spectrum Photosensitive Structures Based on J-Aggregates of Cyanine Dyes

The fabrication processes for narrow-spectrum photosensitive structures based on J-aggregates of cyanine dyes are studied. Two technological approaches are proposed: the electrokinetic deposition of single J-aggregates in the planar electrode configuration and the fabrication of multilayer structures with a sensitive layer of cyanine dye J-aggregates and a transparent electrode made of a conductive carbon nanotube network on a flexible polyethylene naphthalate substrate.

Phonon-Driven Oscillatory Plasmonic Excitonic Nanomaterials.

We demonstrate that coherent acoustic phonons derived from plasmonic nanoparticles can modulate electronic interactions with proximal excitonic molecular species. A series of gold bipyramids with systematically varied aspect ratios and corresponding localized surface plasmon resonance energies, functionalized with a J-aggregated thiacarbocyanine dye molecule, produces two hybridized states that exhibit clear anticrossing behavior with a Rabi splitting energy of 120 meV. In metal nanoparticles, photoexcitation generates coherent acoustic phonons that cause oscillations in the plasmon resonance energy. In the coupled system, these photogenerated oscillations alter the metal nanoparticle's energetic contribution to the hybridized system and, as a result, change the coupling between the plasmon and exciton. We demonstrate that such modulations in the hybridization are consistent across a wide range of bipyramid ensembles. We also use finite-difference time domain calculations to develop a simple model describing this behavior. Such oscillatory plasmonic-excitonic nanomaterials offer a route to manipulate and dynamically tune the interactions of plasmonic/excitonic systems and unlock a range of potential applications.

Near-Infrared Quantum Dot Emission Enhanced by Stabilized Self-Assembled J-Aggregate Antennas.

Enhancing photoluminescent emission (PL) in the near-infrared-infrared (NIR-IR) spectral region has broad applications from solar energy conversion to biological imaging. We show that self-assembled molecular dye J-aggregates (light-harvesting nanotubes, LHNs) can increase the PL emission of NIR PbS quantum dots (QDs) in both liquid and solid media more than 8-fold, promoted primarily by a long-range antenna effect and efficient Förster resonance energy transfer (FRET) from donor to acceptor. To create this composite material and preserve the optical properties of the nanocrystals, we performed an in situ ligand substitution followed by a functionalization reaction using click-chemistry. This resulted in PbS QDs soluble in an aqueous environment compatible with the molecular J-aggregates (LHNs). Theoretical and experimental results demonstrate that long-range diffusive exciton transport in LHNs enables efficient energy transfer to low concentrations of QDs despite there being no direct binding between molecular donors and QD acceptors. This suggests a broad application space for mixed light harvesting and photophysically active nanocomposite materials based on self-assembling molecular aggregates.

Spectral and kinetic features of nonradiative energy transfer in hybrid associates of colloidal quantum dots and organic dyes

The features of nonradiative resonance energy transfer in hybrid associates of colloidal CdS quantum dots (QDs) with molecules of a thiazine dye and J-aggregates of a carbocyanine dye are discussed. The case of an inhomogeneously broadened recombination band of donor (CdS QDs) luminescence is considered. We detected spectral-selective quenching of recombination luminescence of colloidal CdS QDs in association with organic dyes. The maximum of quenching occurs in the region of absorption of the acceptor (organic dye molecule). It is shown using the time-correlated single photon counting technique that the lifetime of the QD luminescence decreases synchronously with the quenching of the luminescence, but only at the wavelengths falling in the region of absorption of the dye. Based on the concept of a donor–acceptor nature of emission of CdS QDs, the dependence of the efficiency of nonradiative energy transfer on the luminescence wavelength is analyzed taking into account the Poisson distribution of its quenchers.

Dye concentration dependence of spectral triplet in one-dimensional photonic crystal with cyanine dye J-aggregate in strong coupling regime

We report on the dye concentration dependence of nonlinear transmission properties of one-dimensional photonic crystal microcavities containing cyanine dye J-aggregates. Using femtosecond nonlinear transmission spectroscopy, we observed a transition from a polariton doublet state to a spectral triplet state over the whole tested concentration range, even at room temperature. In these samples, changes in the dye concentration affected the Rabi splitting energy in the linear transmission measurements; however, we found that changes in the concentration did not greatly affect the triplet formation.

Using cyanine dye J-aggregates as luminescence probe for nanostructured media

Using cyanine dye J-aggregates as luminescence probe for nanostructured media

Surface exciton polaritons supported by a J-aggregate-dye/air interface at room temperature

Surface exciton polaritons (SEPs) are very important for the realization of novel sensors and next-generation optical devices. Here we propose for the first time, to the best of our knowledge, a Kretschmann-Raether device that is able to induce SEPs propagating along the interface between a J-aggregate cyanine dye and air at room temperature. This configuration has the advantages of being straightforward to realize and easy to study because the Kretschmann-Raether approach is the most simple and fundamental from the theoretical point of view. Here a J-aggregate cyanine dye produces strong binding energy due to Frenkel excitons, and this enables the observation of SEPs easily at room temperature. One of the advantages of the use of the J-aggregate cyanine dye is the simple device preparation. This is because the J-aggregate cyanine dye can be easily deposited on any arbitrary substrates with a spincoating or dip-coating technique from its aqueous solution in ambient condition. We observed SEPs at room temperature, and the deepest resonant peak was obtained for a 94nm thick 5,6-dichloro-2-[[5,6-dichloro-1-ethyl-3-(4-sulfobutyl)-benzimidazol-2-ylidene]-propenyl]-1-ethyl-3-(4-sulfobutyl)-benzimidazolium hydroxide film at 532nm wavelength. Our results may pave the way for the realization of novel SEP biosensors in a simple and straightforward way at room temperature.

Organic Exciton in Strong Coupling with Long-Range Surface Plasmons and Waveguided Modes

In this Letter, we demonstrate experimentally the strong interaction between organic semiconductor excitons and long-range surface plasmons. For this purpose, a thin J-aggregated cyanine dye layer is deposited on a thin silver film bounded by two poly(vinyl alcohol) layers. An anticrossing between the long-range surface plasmon and the dye exciton is measured in the dispersion relation and confirmed in luminescence experiments, showing unambiguously the hybridization between the long-range surface plasmon and the dye exciton. The extension of the polaritonic states deduced from the dispersion curves is 50 μm, which represents an increase of more than 1 order of magnitude compared to usual surface plasmon-based polaritons. We believe that the extension of the polariton coherence length can have direct applications to the energy transfer between molecules over long distances in strong coupling, as well as in the modification of the properties of materials (conductivity, second harmonic generation). Strong c...

Structural templating of J-aggregates: Visualizing bis(monoacylglycero)phosphate domains in live cells

Identifying the key structural and dynamical determinants that drive the association of biomolecules, whether in solution, or perhaps more importantly in a membrane environment, has critical implications for our understanding of cellular dynamics, processes, and signaling. With recent advances in high-resolution imaging techniques, from the development of new molecular labels to technical advances in imaging methodologies and platforms, researchers are now reaping the benefits of being able to directly characterize and quantify local dynamics, structures, and conformations in live cells and tissues. These capabilities are providing unique insights into association stoichiometries, interactions, and structures on sub-micron length scales. We previously examined the role of lipid headgroup chemistry and phase state in guiding the formation of pseudoisocyanine (PIC) dye J-aggregates on supported planar bilayers [Langmuir, 25, 10719]. We describe here how these same J-aggregates can report on the in situ formation of organellar membrane domains in live cells. Live cell hyperspectral confocal microscopy using GFP-conjugated GTPase markers of early (Rab5) and late (Rab7) endosomes revealed that the PIC J-aggregates were confined to domains on either the limiting membrane or intralumenal vesicles (ILV) of late endosomes, known to be enriched in the anionic lipid bis(monoacylglycero)phosphate (BMP). Correlated confocal fluorescence - atomic force microscopy performed on endosomal membrane-mimetic supported planar lipid bilayers confirmed BMP-specific templating of the PIC J-aggregates. These data provide strong evidence for the formation of BMP-rich lipid domains during multivesicular body formation and portend the application of structured dye aggregates as markers of cellular membrane domain structure, size, and formation.

Accelerating FRET between Near-Infrared Emitting Quantum Dots Using a Molecular J-Aggregate as an Exciton Bridge.

Fast energy transfer (EnT) among quantum dots (QDs) with near-infrared (NIR) emission is essential for fully exploiting their light harvesting and photon downconversion (multiexciton generation) abilities. This paper demonstrates a relayed EnT mechanism that accelerates the migration of NIR excitons between PbS QDs by a factor of 20 from that of one-step EnT through a polyelectrolyte and even a factor of ∼2 from that of one-step EnT between QDs in direct contact, by employing a J-aggregate (J-agg) of a cyanine dye as an exciton bridge. The donor QDs, acceptor QDs, and J-agg are electrostatically assembled into a sandwich structure with layer-by-layer deposition. Estimates of EnT rate and yield from transient and steady-state absorption and photoluminescence spectroscopies show that the rate-limiting step in the relay is EnT from the donor QD to the J-agg, while EnT from the J-agg to the acceptor QD occurs in <10 ps. A comparison of this system to the analogous solution-phase system suggests that the overall donor-to-acceptor EnT yield in the relay (18%) can be improved by depositing the J-agg with more intermolecular order. This work demonstrates the viability of relayed EnT through a molecular bridge as a strategy for accelerating long-distance exciton migration in assemblies of QDs, in particular in the near-infrared.

Effect of nano clay Laponite on stability of SHG active J-aggregate of a thiacyanine dye onto LB films

We have investigated the stability of Second Harmonic Generation (SHG) active J-aggregate of a thiacyanine dye N, N′-dioctadecylthiacyanine perchlorate (TC18) in Langmuir-Blodgett (LB) films in presence and absence of a synthetic clay mineral Laponite. Surface pressure vs area per molecule isotherm was taken to observe the monolayer stability and UV–vis absorption, deconvolution of the absorption spectra, Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) etc. have been employed to investigate the stability. It has been observed that pure TC18 J-aggregates degrades with irradiation of light, passage of time as well as post heat treatment of the TC18 J-aggregated LB films. However, in case of TC18 – Laponite hybrid films the decrease in J-aggregate is minimal. Interestingly, it was observed that the relative humidity plays a major role in the reconstruction of the J-aggregate in the treated film and thereby stabilizes the J-aggregate. Both pure TC18 and TC18 – Laponite hybrid LB monolayer films are found to be SHG active. In case of TC18 – Laponite hybrid film SHG signal shows better stability.